1. Field of the Invention
This invention relates to fixtures for retaining electronic substrates during various assembly and test operations.
More particularly, the present invention relates to a construction of the fixtures which simplifies the fabrication and use.
In a further and more specific aspect, the instant invention concerns an improved substrate retention fixture and the use of the fixture in various assembly and testing operations for flat substrates and the like.
2. Prior Art
In general, assembly and test operations on substrates, such as printed circuit boards, hybrid circuits, etc. are performed either manually or automatically. Because of the large number and complexity of circuitry and components being positioned on substrates at the present time (and the trend for this to increase in the future), there is a definite advantage in performing the assembly and test operations, or as much as possible, automatically.
One major problem that arises during either manual or automatic operations is damage to the substrate. Most substrates are positioned by alignment pins which engage alignment holes on the substrate or by accurately formed edges of the substrate. In either case, if the substrate is aligned and moved often the holes and/or alignment edges have a tendency to wear, nick, or otherwise become damaged. Once such damage occurs further automatic (and in some instances manual) operations may become either very difficult or impossible.
Another problem arises when a variety of different sized or shaped substrate are being operated upon. In many instances it is very difficult to modify the assembly line, especially automatic assembly lines, to accept different sized and/or shaped substrate.
In the prior art, to at least partially overcome some of these problems work holders have been devised to grip a substrate and hold it during one or more operations. As a specific example, work holders have been devised to hold printed circuit boards during passage through flow solder machines. One major problem with these prior art work holders is that they are designed for a specific operation and the printed circuit boards must be removed after the operation (flow soldering in this example) is completed.
A second problem that is prevalent in prior art work holding devices is the extreme complexity involved in both the fabrication of the work holding device and in the use of the work holding device. Generally, the prior art work holding devices are constructed with relatively large and involved levers or sliding and locking components. In the case of levers, the substrate is positioned in the work holding device and then a plurality of levers are twisted or otherwise moved manually to lock the substrate in place. Sliding and locking components generally take the shape of entire edges that slide on a base member to engage a correctly positioned substrate. The sliding edge or other component is then locked in place by means of locking levers, screws, or other complicated locking mechanisms.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide an improved substrate retention fixture.
Another object of the present invention is to provide an improved substrate retention fixture that is relatively simple to operate.
And another object of the present invention is to provide an improved substrate retention fixture that can be used to retain substrates with different sizes and shapes.
Still another object of the present invention is to provide an improved substrate retention fixture which is simpler to fabricate than other work holders.
Yet another object of the present invention is to provide an improved substrate retention fixture which is lighter than prior art work holders.
And still another object of the present invention is to provide an improved substrate retention fixture which is less expensive to fabricate and use than prior art work holders.
A further object of the present invention is the provision of an improved substrate retention fixture which can be used with a variety of modern automated machines.
And a further object of the present invention is the provision of an improved substrate retention fixture which is more versatile than prior art work holders.
Another object of the present invention is to provide an improved substrate retention fixture which will retain the substrate securely without extending mechanisms above the top surface of the substrates.
And another object of the present invention is the provision of a fixture to pull thin flexible substrates flat, which may otherwise be bowed or curled in their free state.